EFFECT OF WATER-SUPPLY AND SALINITY ON PIMA COTTON

A field study was conducted in northwestern Negev to determine the eff ect of the amount of water and its salinity level on the yield of Pima cotton (cv. S5). Irrigations were applied by means of a double line-s ource sprinkler system using two parallel lines, each supplied with wa ter of a different salinity. The water salinity ranged from 2 to 7.5 d S m(-1) and the seasonal water application ranged from 30.0 to 68.0 cm . With water amounts of up to 50.0 cm (42% of Class A evaporation), an increase in water salinity caused a reduction in the seed cotton yiel d and the salinity threshold increased with an increasing amount of wa ter. The maximum yield of seed cotton (about 5000 kg ha(-1)) was obtai ned with a water application of 50 cm and a water salinity between 4 t o 5 dS m(-1). With seasonal water applications exceeding 50 cm, an inc rease in salinity increased the yield. This is attributed to a depress ion of excessive vegetative growth in the presence of large amounts of water. (C) 1998 Elsevier Science B.V. All rights reserved.